MAP Sensor Calibration

[alschief]

I am troubleshooting the possible low power of an UL Power Fuel Injected engine. The Map Sensor is showing 1.4 inches lower than the field barometric pressure. Is there a calibration procedure to adjust the supplied sensor reading?
The UL Power engine managment system does not use the Dynon Supplied sensor

 

[dynonsupport]

There is no adjustment for MAP. However, MAP only matches your field baro setting if you are at sea level. How high up are you when doing this? 1.4 inches is about 1,200 ft MSL.

 

[mmarien]

I think it's normal for the MAP to be lower than the barometric pressure based on your altitude. I think the rule is one inch/1000 feet. See below.

Also check out this article: Manifold Pressure Sucks

 

[alschief]

We are at 1,500' so I guess that matches the reading.


AL

 

[Battson]

We are also above SL by a few hundred feet - yet MAP always reads 30.04"Hg whether we're under a high or low pressure system... is that bad?

 

[dynonsupport]

Given that the MAP only reads in tenths, that does sound bad... and impossible

Are you sure you are looking at the right thing?

 

[Dynon]

Actually Battson - that sounds like you're talking about your altimeter (BARO) setting on the PFD, not your MAP (manifold pressure) for the engine.

 

[Battson]

No, just a typo - it reads 30.4"hg each time I turn on the engine mangement system.

 

[mmarien]

Are you turbo charged? :-? Should read ~12 at idle.

 

[Battson]

*management system

 

[Dynon]

You might check if the hose going the MAP sensor is crimped or clogged in some way. You should see some variation in the MAP when the engine's off from day to day. Has the engine been started yet? Does it read appropriately lower then?

 

[Battson]

The hose is straight and seems clear, good thought mind you. It does have a few connections in it, but a leaky join would only cause a problem if the engine was sucking...

I will not be able to go back and start the engine for a few weeks now, but I'll check when I do. If it's only 0.5"Hg out then I am not really sure how I'll test for that when it's running. Any thoughts?

 

[Dynon]

Well, another thing you could do is pop off the connection from the engine and apply a little suction. As for engine start - the moment you start your engine, assuming you're not running it wide open - your MAP reading should rocket down to under 15"